1. Technical Field
The technology described herein relates generally to wireless networking. More particularly, the technology relates to the communication of user specific control information in a wireless local area network (WLAN), including coding of the user specific control information.
2. Description of the Related Art
Wireless LAN (WLAN) devices are currently being deployed in diverse environments. Some of these environments have large numbers of access points (APs) and non-AP stations in geographically limited areas. In addition, WLAN devices are increasingly required to support a variety of applications such as video, cloud access, and offloading. In particular, video traffic is expected to be the dominant type of traffic in many high efficiency WLAN deployments. With the real-time requirements of some of these applications, WLAN users demand improved performance in delivering their applications, including improved power consumption for battery-operated devices.
A WLAN is being standardized by the IEEE (Institute of Electrical and Electronics Engineers) Part 11 under the name of “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications.” A series of standards have been adopted as the WLAN evolved, including IEEE Std 802.11™-2012 (March 2012) (IEEE 802.11n). The IEEE Std 802.11 was subsequently amended by IEEE Std 802.11ae™-2012, IEEE Std 802.11aa™-2012, IEEE Std 802.11ad™-2012, and IEEE Std 802.11ac™-2013 (IEEE 802.11ac).
Recently, an amendment focused on providing a High Efficiency (HE) WLAN in high-density scenarios is being developed by the IEEE 802.11ax task group. The 802.11ax amendment focuses on improving metrics that reflect user experience, such as average per station throughput, the 5th percentile of per station throughput of a group of stations, and area throughput. Improvements may be made to support environments such as wireless corporate offices, outdoor hotspots, dense residential apartments, and stadiums.
A Physical Layer Protocol Data Unit (PPDU) transmitted in an HE WLAN may include user specific control information in an HE Signal B (HE-SIG-B) field. To reduce overhead in the HE WLAN, efficient encoding the information in the HE-SIG-B field may be used.
The HE-SIG-B field is encoding using one of a 1/2, 2/3, 3/4, and 5/6 coding rate. That is, for each bit in the HE-SIG-B field, an average of 2, 1.5, 1.333, or 1.2 bits are encoded for transmission. The bits to be encoded may be generated by producing 2×N bits from N bits of the HE-SIG-B field and then removing some of the 2×N bits. For example, a 3/4 bit rate may be generated by generating 6 bits from each 3 bits of the HE-SIG-B field and then removing two of each of the generated 6 bits, and a 5/6 bit rate may be generated by generating 10 bits from each 5 bits of the HE-SIG-B field and then removing four of each of the generated 10 bits. This process is known as rate matching, and the removal of bits may be referred to as puncturing. Generally, the puncturing is done according to a pattern (a puncturing pattern) determined by the coding rate.
Depending on the coding rate chosen, subfields of the HE-SIG-B field may not start at boundary used by to perform rate matching.